The Gordon Research Conferences bring together active investigators in a given are of research for the purpose of in-depth communication, exchange of new and unpublished information and technologies, and free discussion of ideas that will stimulate and strengthen research efforts in the field. The 1988 Conference on Hormone Action represents the 18th conference in a series which began in 1969. As in recent years, this conference will promote the exchange of information about the rapidly growing field of molecular and cellular endocrinology. The conference this year will have several sessions on integrative topics in which the focus will not be a single hormone system, but rather a broader biologic problem which involves the actions of multiple hormones. For example, two sessions will discuss hormones and development, emphasizing hormonal regulation of the molecular mechanisms controlling developmental processes in several experimental systems. The Sunday night plenary speaker will highlight this focus. Another session will deal with hormonal regulation of proteolysis, and another with growth factors, oncogenes, the extracellular matrix and tumor cell invasion and metastases. The session on the regulation of gene expression by hormones will attempt to focus on the combinatorial action of multiple hormones. In addition there will be sessions focusing on G proteins and signal transduction, and on insulin and insulin-like growth factors. This conference brings together a diverse group of scientists studying a spectrum of organisms ranging from the fruit fly to mouse and man. The participants range from basic scientists studying fundamental molecular aspects of hormonal regulation to physiologists and physician-scientists interested in the integrative actions of hormones and their applications to human disease. The limited attendance policy coupled with an open poster session policy promotes broad participation and maximal interchange among conferees. The Gordon Conference policy of not publishing results from this conference, encourages the presentation of recent developments and new ideas. The Gordon Conference Foundation generously supports these conferences but cannot supply sufficient funds to cover all expenses. Solicitation of private funds is not allowed. Therefore sources of support such as the National Institutes of Health are critical to the continued success of this conference.